<!DOCTYPE html>
<html>

<head>
    <title>Example</title>
    <style>
        div {
            overflow: hidden;
            white-space: nowrap;
            text-overflow: ellipsis;
        }
        
        #aDiv {
            width: 100px;
        }
        
        button {
            margin-bottom: 2em;
        }
    </style>
</head>

<body>
    <div id="aDiv">
        FooBar-FooBar-FooBar-FooBar
    </div>
    <button id="aButton">
        Check for overflow
    </button>
    
    <div id="anotherDiv">
        FooBar-FooBar-FooBar-FooBar
    </div>
    <button id="anotherButton">
        Check for overflow
    </button>
</body>
<script>
    var buttonOne = document.getElementById('aButton'),
    buttonTwo = document.getElementById('anotherButton'),
    divOne = document.getElementById('aDiv'),
    divTwo = document.getElementById('anotherDiv');

    //check to determine if an overflow is happening
    function isOverflowing(element) {
        return (element.scrollWidth > element.offsetWidth);
    }

    function alertOverflow(element) {
        if (isOverflowing(element)) {
            alert('Contents are overflowing the container.');
        } else {
            alert('No overflows!');
        }
    }

    buttonOne.addEventListener('click', function() {
        alertOverflow(divOne);
    });

    buttonTwo.addEventListener('click', function() {
        alertOverflow(divTwo);
    });
</script>
</html>
